Undo and Redo

Undo option allows to cancel or remove the last changes taken place in the document such as editing, formatting etc.

Redo option allows to repeat the last changes that canceled by undo operation.

Open the existing file (For example, report.odt) and then start editing in it.
If, by mistake, you have made some changes and now you want to erase the last change done, then use the Undo option.
After undo command, again if you want to go back then use the Redo option.